Image fade, which includes light and ambient air fade, is being recognized as a significant problem to overcome in ink jet printing. Earlier concerns dealt, for example, with water fastness and smear fastness. These earlier concerns have been largely overcome, and the fading of images, especially that of color images, with time has become an important issue.
One prior art solution involves the inclusion of image fade additives to the ink. However, this complicates the ink and the results have not been very promising. Inclusion of additives often reduces the reliability of the ink.
Another prior art solution involves inclusion of the additive into the media coating, which is typically silica (silicon dioxide) or silica-based. The disadvantage is that this does not yield a uniform and a homogeneous layer of the additive on the porous media surface. As a result, colorant molecules of the printed image get exposed to different chemical environments.
Yet another prior art solution is to use swellable coatings on the media that in general show better image permanence. The major disadvantages to this approach are the poor inherent dry time and wet fastness.
Thus, there is a need for reducing image fade without adversely affecting either the ink or the print medium.